Process of producing maleic acid



C. R. DOWNS.

PROCESS OF PRODUCING MALEIC ACID.

APPLICATION FILED mu 3. 1920.

1,374,720. Patented A r. 12, 1921.

Fly; 2.

INVENTOR ATTORNEY of New Jersey, have.invente and useful Improvements in Processes of.

UNITED STATES PATENT OFFICE.

CHARLES R. DOWIISyOI' OLIFFBIDE, NEW JERSEY, ABB IGNOB TO THE BARRETT CODA, A CORPORATION 01' NEW JERSEY.

PROCESS OF PBODUCING IALEIC ACID.

To all whom it may concern:

Be it known that I, CHARLES R.'D OWNS, a citizen of the United States, residin at Clifi'side, in the-county of Ber n and tate certain new Producing Maleic Acid, of which the following is a specification.

This invention is for a process of producing maleic acid from benzene. By this invention use is made of the rinciple that vaporizable liquids will absor latent heat in changing from the liquid to the vapor.

state without change in temperature, the

heat being carried away by the vapors, from which it may be extracted, thereby condensing the vapors which ma be returned for absorbing more heat. of my application Ser. No. 303,337 filed June '11, 1919.

The invention will be described and illustrated in connection with apparatus in which a gaseous reaction mixture is brought into contact with a catalystin which or in roximity to which there are coi itai ners or a vaporizable liquid or liquids, said containers being provided with means for lead ng ofi vapors to a cooling s ace and returning the condensed liquid. T ere may be one or m'ore containers for the liquid and they should be so shaped and disposed that heat will be readily transmitted from the.catalyst to the vaporizable liquid. It is to be understood that the invention is not restricted to the particular apparatus shown, nor to the materials mentioned.

In the drawings Figure 1 is a section through a form of apparatus for carrying out the process, and

ig. 2 is a section through a modified form of the apparatus.

. In Fig. 1 the reference character 1 refers to a container which is 1 Jvided with a perforated plate 2 upon w ieh a layer of catalyst 3 or carrier such as pumice or asbestos for said catalyst, is placed. Electrical heating means are shown at 4 and a series of pipes 5 with closed ends extend into the catalyst 3 or the carrier for the same. The upper ends of the pipes 5 term nate in a header-6 which may connected to a pump 7 which may be used eitherto create a vacuum or pressure in the pi e or to introduce a gas, preferably neutra into the header Specification of Letters Patent.

his is a division- Patented Apr. 12, 1921. and am application illed'luly a,

from a source, not shown. A valve V in the pipe P may be closed, if desired, after tamer 1 which has an inlet 9 and the con- -tainer 1 is surrounded by a casing or houslet 12.

In the modification shown in Fig. 2, the container 1 is provided with an outlet 12, and a pipe 13 leads to the inlet 9 from the acket 14 which surrounds the upper portion of the tubes 5 The other parts shown in Fig. 2 are similar to the corres nding parts described in connection with ig. 1.

The operation according to Fig. 1 is as follows: The reaction mixture is introduced through inlet 1 into container 1 where it comes into contact with the catalyst 3. If necessary, the heater 4 may first bring the temperature up to that required to initiate the catalytic reaction which is'an exothermic one. The catalyst 3 becomes heated and the heat is conducted through the walls of the tubes 5 to the liquid therein which is caused to boil and the vapors rise in the tubes 5, the upper endsof which are cooled in any convenient way so that the vapors become condensed and trickle back into the lowerends of the tubes 5. The liquid in the tubes products may be collected and used. The

operation according to Fig. 2 is the same as that above described in connection with Fig.

ing 10 having a partition 11 and an out-' 1 except that the reaction mixture is passed through jacket 14 so as to come into contact with the catalyst 3 The products of re action pa out through the outlet 12.

A speci 0 application of this invention is tion to pro ess too-far, and the, reactionin the oxidation of benzene to maleic a'cid in the presence of vanadium oxid 9.8.8. catalyzer. It has been found that the. proper temperature at which this reaction should be carried out is about 400 C. because very' much higher temperatures cause-fthe oxidawill not ta e place satisfactorily at very much lower temperatures. Mercury boils at 357 C. and if proper pressure is applied. upon the mercury its boiling point .is

changed' sufiiciently so that a mixture of an oxygen containing gas and benzene in thevapor phase is passed into the catalyst the exothermic reaction to produce inaleic acid will raise the temperature enough to provide sufiicient tem erature radient or eadbetween the cata yst 3 an the liquid in tubes 5 when this liquid is mercur so V that the exothermic heat is transmitted rom the catalyst 'to the mercury with suflicient rapidity to keep the temperature of the catdensing of all the vapors, and the pressure maintained in the pipes will be such as to kee so t at it will hold the catalyst at the proper tem rature. 'When mercury or other oxidiza le liquid is used as the heat removing a my it may be advisable to introduce into t 1e tubes 5 a neutral gas, such as nitrogen, to preventoxidation of the liquid.

It is obvious that the' )rinciple of this invention may be applie in 'difie'rent ways without departing from the spirit and scope of the invention, and the tem erature may be controlled in many other tions by using other liquids of different boiling 'oints or the bo'ilin points of the d s used canbecontro led within somew at wide limits byrchanging the pressure inside the tubes 5. we or more streams of liquids or gases, or a mixtureof the-same with solid materials, which react exothermically 'when'brought-into contact may' have theirtemperatures controlled during the repl the boiling point of the liquid mercury iemical reacaction herein described. Further examples of chemical reaction to which this invention is applicable are the oxidation of anthracene to anthra uinon, toluene to benzoic acid and benzal ehyde, na hthalene to phthalic anhydrid, ethyl alcoho to acetaldeyde, and the chlorination of hydrocarbons,

etc. Other applications of this invention at not necessary to describe will readilyoceur to those skilled in the art.

I claim: v

1. In the manufacture of maleic acid by the' partial oxidation of benzene by an oxy- 6| gen containing gas in the presence of a'suit- -ablc catalyzer, the step which; comprises providing liquid mercury out of contact with the reaction mixture but in heat transfer-ring relationshi 2. In the manu acture of maleic acid by the partial oxidation ofbenzenc by an oxygen containing gas in the presence of a suitable catalyst, the steps which comprise supplying liquid mercury to the zone of re- 7 action out of contact with the reaction mixture but in heat transferring relationship to said catalyst so that heat will be absorbed by said mercury as latent heat of vaporization and maintaining the supply of liquid mer- 8 cury in the reaction zone b introducing liquid mercury before all o the original mercury has been vaporized.

3. In the art of gas phase oxidation of benzene in the (presence of a catalyst to 8 form maleic aci the improvement which comprises maintaining a substantially constant and uniform temperature by the vaporization of a liquid distributed within the zone of reaction out of direct contact with 9 the catalyst but in heat transferringv relationship thereto.

.4. In the art of gas phase oxidation of benzene in the (presence of a catalyst to form maleic aci comprises mainta ning a silbstantiallv constant and uniform temperature by the vuporization of mercury distributed within the zone of.reaction out'ofdirect contact with the catalyst but in heat transferring ie- 1 lationship thereto.

In testimony whereof I aflix my signature.

CHARLES agnowu s.

thereto. 71

'the improvement which I 

